Heat sink for a. c.-d. c. rectifier



Sept. 11, 1962 R. c. SABiNS 3,054,032

HEAT SINK FOR A.C.-D.C. RECTIFIER Filed Nov. 17, 1958 INVENTOR.' ROLLAND C. SABINS a, ATTORNEYS United States Patent Ofifice Patented Sept. 11, 1962 3,054,032 HEAT SINK FOR A.C.-D.C. REQITIFIER Roliand C. Sabins, 522 flataiina Blvd, San Diego, Calif. Fiied Nov. 17, 1958, Ser. No. 774,328 6 Qlaims. (Cl. 317-234) The present invention relates to a heat sink and more particularly to a heat sink for an electric element or device such as a diode.

The present invention relates to an electrical assembly such as an A.C.-D.C. rectifier employing a diode and a lgeat sink in intimate heat exchange relationship with the iode.

In practicing the present invention, I employ, as a heat sink, a block of high thermal conductive material, such as high thermal aluminum. The base of the diode is secured to the block in intimate heat exchange relationship. I provide a large number of holes extending through the block so as to materially increase the heat exchange area between the block and the environment, for example the air thereabout. Preferably these holes are arranged in a circle whose axis is approximately at the center of that area of the diode that engages the block.

Further objects and advantages will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the invention is illustrated.

In the drawings:

FIG. 1 is a front View of an A.C.-D.C. rectifier including the cabinet, the front panel being removed to more clearly show interior mechanism therein;

FIG. 2 is a side view of the cabinet;

FIG. 3 is a plan view of an assembly including three superimposed sinks each carrying two diodes, the three sinks being mounted upon an insulating panel, the structure of FIG. 3 being on a larger scale than in FIGS. 1 and 2;

FIG. 4 is a fragmentary view on twice the scale of the upper left corner of FIG. 3; and

FIG. 5 is a sectional view taken on line 5-5 of FIG. 4, the elements being shown on a larger scale.

Referring more in detail to the drawings, the A.C.- D.C. rectifier is shown generally at and includes a cabinet 22 preferably formed of sheet metal. The front wall 23 of the cabinet is provided with an opening 24 which is normally closed by a removable panel 26. The front of the cabinet also carries electrical meters 28 and 30. The rear wall of the cabinet is shown at 32 and the side walls, which are the same, are shown at 34 and 36. The front wall 23 of the cabinet carries two blowers 38 and 40 which are driven by a motor 42. These blowers may be of the sirocco type having inlets one of which is shown at 44.

The upper portions of the side walls 34- and 36 are cut away and each of these cut away portions is closed by a panel 46. This panel is formed of dielectric material and preferably fiber glass. It will be understood that each of these walls 34 and 36 carries a panel 46. FIG. 3 is a View of one of these panels looking in the direction of arrow 3 of FIG. 1. The same may be said with respect to FIG. 4, and it will be seen from FIG. 4 that the panels are provided with holes 48 for attaching the same to the cabinet by screws or bolts passing through the holes 48.

Diodes 50 are provided preferably of the silicon type, and in the instant embodiment these diodes are of the ZOVM type rectifiers manufactured by Sarkes Tarzian, Inc., Rectifier Division, 415 North College Avenue, Bloomington, Indiana, and are illustrated on page 28 of that companys catalog No. 669Al (revised June 1957). More specifically these diodes are rated as follows: Maximum peak inverse volts 200; maximmn R.M.S. volts 140; and in current rating of amperes these diodes in a full wave bridge (4 required) are rated to deliver 200 amperes D.C. maximum current at 125 volts D.C. providing the temperature does not exceed 100 degrees centigrade. Six of these diodes are shown and may all be carried by one heat sink, but for various bridge relationship purposes, I provide three sinks, each a half wave bridge, 52, 54 and 56 which are superimposed, each carrying two diodes, an equal number on the opposite side of the cabinet 22, providing a triple full Wave bridge assembly. The base 58 of each diode is provided with a flat surface 60 which is in intimate heat exchange relationship with the flat surface 62 on a sink and these bases are held in intimate heat exchange relationship with the sinks by three screws 64 for each base. A stranded wire 66 is connected to the diode 5t) opposite the base 58 and is provided with a fastening terminal 68.

The sinks or blocks 52, 54 and 56 are formed of a high thermal heat conductive material such as high thermal aluminum for the ready dissipation of heat from the diode to the heat sink. A series of holes are drilled through the heat sinks and the panel 46. In the instant embodiment fourteen holes 70 are arranged in a circle, the axis of the circle coinciding with the axis of the diode; in this manner heat is dissipated equally radially from the diodes. The blowers force air about the diodes and through the openings 76 to the exterior of the cabinet. The large volume or mass of the block of high thermal heat conducting material quickly absorbs the intense heat at the base of the diode and the surfaces of the block quickly dissipate the heat; I prefer to use diodes having a delivery value in amperes of twice that of the demand. For example, the diodes, as above rated, are for a demand of only approximately 100 amperes DC. at a maximum voltage of 125 volts DC. In such installation, I employ a high thermal aluminum block 12 x 4 /3 x 2 inches for two diodes and with fourteen holes of one-half inch in diameter for surrounding each diode. Thus the surface composite area of the walls forming the twenty-eight holes should be approximately fifty percentum of the area of the total surface area of a two diode block. This one to two ratio of holes surface areas and the surface block area prevails for all sizes of diodes. For example a sink for a two diode block, in

' which the demands on the diodes are twice that of the example heretofore set out, namely demands of 200 amperes, then the composite surface area of the walls forming the holes should be twice that of the example heretofore set out, and likewise the total surface area of the block should be twice that of the example heretofore set out.

To further enhance the heat exchange from the diodes to the sinks and the environment air, I surround the diodes 50 with a ring 72. This ring is formed of high thermal heat conductive material such as high thermal aluminum. It is spaced concentrically of the diode, and the space is filled with a high heat conductive material 74 of the dielectric type. This material 74 may be of the epoxy type containing granules or threads of high heat conducting material. This ring 72 is secured in intimate heat exchange relationship with the sink by screws 76. The material 74 and ring 72 not only provide for the ready heat exchange from the diode to the environment air and the heat sink, but also enhance the physical sturdiness of the diode. It will be observed that the sink extends outwardly sufficiently to provide coverage for at least a part of the stranded wire 66 by the heat conducting material 74.

By reason of the present invention sufiicient heat is conducted from the diodes 50 so as to prevent injury to the same even when such diodes are subjected to surge 3 currents. The material 74, the ring 72 and the surface 62 of the heat sink block readily conducts heat from the diode t and this heat is quickly dissipated through the rear and front faces of the sink, the ends of the sink, and the surfaces of the holes 70 as the air passes through the holes 70. Also considerable heat is dissipated directly from the material 74 and the ring 72 to the air passing over those elements.

By reason of the present invention, I have materially reduced the size and weight over rectifiers heretofore used; in many instances such reduction was approximately fifty percent.

It will be understood that the connections 68 are suitably connected either directly to a source of AC. current or through a transformer 78 while one bank of sinks on one side of the cabinet provides a positive outlet for the rectified current and the other bank of sinks provides a negative outlet for the rectified current. The conductor for one of the outlets of the DC current is shown at 80 at FIG. 3. This conductor is insulated by a sheath 82. The conductor St} is suitably connected to each of the sinks 52, 54- and 56 by connectors 84.

While I have shown blowers for circulating air through the cabinet and about and through the heat sinks, it will be understood that such blowers are merely for illustrative purposes and that, in certain insulations, sufficient air is circulated by convection. Too, in certain instances it may be more desirable to space the sinks from one another. Thus air can also pass between the sinks.

While the form of embodiment herein shown and described constitutes a preferred form, it is to be understood that other forms may be adopted falling within the scope of the claims that follow.

I claim:

1. An A.C.-D.C. rectifier assembly comprising in combination, a diode; and a cabinet including a wall for supporting the diode within the cabinet, said Wall being in intimate contact with the diode and comprising a block of high thermal conductive material such as high thermal aluminum, said wall having holes extending therethrough and disposed in a circle immediately about the diodes for circulation of a cooling medium, the thickness of the block and the number and the diameter of the holes are so proportioned that the composite radiating area surface of the walls forming the holes is approximately fifty percentum of the external radiating surface of the block.

2. An A.C.D.C. rectifier assembly comprising in combination, a diode, said diode including a base having a flat outer surface; and a cabinet including a wall for supporting the diode within the cabinet, said Wall having a flat surface in intimate contact with the flat surface of the base of the diode, said wall comprising a block of high thermal conductive material such as high thermal aluminum, said wall having holes extending therethrough and disposed in a circle immediately about the diode for circulation of a cooling medium, the thickness of the block and the number and the diameter of the holes are so proportioned that the composite radiating area surface of the walls forming the holes is approximately fifty percentum of the external radiating surface of the block.

3. An A.C. D.C. rectifier assembly comprising in combination, a diode having a base and a conductor extending from the diode; a wall, said base of the conductor being supported by the wall in intimate heat conducting relationship, said wall comprising a block of high thermal conductive material such as high thermal aluminum, said wall having holes extending therethrough for circulation of a cooling medium; a casing spaced from and surrounding the diode, said casing being formed of high thermal conductive material such as high thermal aluminum; and a heat conducting material embedded in the casing and surrounding the diode.

4. An assembly as defined in claim 3 characterized in that the composite area of the walls forming the holes in approximately fifty percentum of the external surface of the block.

5. An A.C.-D.C. rectifier assembly comprising in combination, a diode having a base and a conductor extending from the diode, said base having a flat outer surface and a wall for supporting the diode, said wall having a flat surface in intimate contact with the flat surface of the base of the diode, said wall comprising a block of high thermal conductive material such as high thermal aluminum, said wall having holes extending therethrough for circulation of a cooling medium; a casing spaced from and surrounding the diode, said casing being formed of high thermal conductive material such as high thermal aluminum; and a heat conducting material embedded in the casing and surrounding the diode.

6. An assembly as defined in claim 5 characterized in that the composite area of the walls forming the holes is approximately fifty percentum of the external surface of the block.

References Cited in the file of this patent UNITED STATES PATENTS 1,975,658 Marshall Oct. 2, 1934 2,353,461 Hamann July 11, 1944 2,471,011 Shapiro May 24, 1949 2,730,663 Harty Jan. 10, 1956 2,876,399 Koenig Mar. 3, 1959 2,917,686 Boyer Dec. 15, 1959 

